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A new theory of the photoplastic effect in coloured alkali halide crystals

S. TIWARI1, A. S. GOUR2, V. K. JOGI1, B. P. CHANDRA3

Affiliation

  1. School of Studies in Electronics, Pt.Ravishankar Shukla University, Raipur 492010
  2. School of Studies in Physics, Pt.Ravishankar Shukla University, Raipur 492010
  3. Disha Institute of Management and Technology, Raipur 492101, (C.G.)

Abstract

A new theory of the photoplastic effect (PPE) in colored alkali halide crystal, which is based on the interaction between moving dislocation and photo-obstacles has been formulated. When a colored alkali halide crystal is illuminated by light with certain wavelength during its plastic deformation, the increase or decrease in flow stress occurs because the photo-ionized electrons from F-centers influence the motion of deformation bleaching and photo-ionized electrons from F-centers influence the motion of deformation bleaching and interaction of moving dislocations with F-centers, expressions are derived for the PPE, like temporal , deformation, strain-rate, spectral, light intensity, coloration, dimension and thermal characteristics of PPE. A good agreement is found between the theoretical and experimental results. It is shown that the PPE provides a sensitive tool for determining the lifetime of dislocation-captured F-centers in crystals. It is shown that in certain crystals the radius of interaction between F-centers and moving dislocation may increase with their deformation..

Keywords

Photoplastic effect, Plastic deformation, Alkali halides, Color centers.

Submitted at: Aug. 5, 2010
Accepted at: Sept. 15, 2010

Citation

S. TIWARI, A. S. GOUR, V. K. JOGI, B. P. CHANDRA, A new theory of the photoplastic effect in coloured alkali halide crystals, Journal of Optoelectronics and Advanced Materials Vol. 12, Iss. 9, pp. 1840-1851 (2010)